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Transfer Switch Path Rating Calculator

Compare actual transfer-switch normal and generator current-path ratings with a documented service or selected-load design and save the basis.

Use this result well

Inputs that matter
Documented connection topology, One-line design and rating basis, Required normal-path rating (A), Required emergency-path rating (A), and 2 more
Output to expect
Transfer-switch path rating comparison
  • Check the units and required inputs before comparing results.
  • Keep the assumptions with a copied result so you can reproduce the calculation later.
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Reference & details

How it works

Transfer-switch path rating comparison

Screen actual transfer-switch candidates against independently specified normal and emergency current-path requirements. A whole-service installation can need a 200A normal path with a much smaller generator path. These requirements must come from the approved topology and protection design, not min(service A, generator A).

A candidate fits when normal-path rating ≥ required normal-path A AND emergency-path rating ≥ required emergency-path A.

Updated: September 2026

Example Scenarios

Try the built-in example, then replace its source data with your actual documented values. Retain failed comparisons and unresolved decisions.

→ Service candidate — current-path candidate

FAQ

Screen actual transfer-switch candidates against independently specified normal and emergency current-path requirements. A whole-service installation can need a 200A normal path with a much smaller generator path. These requirements must come from the approved topology and protection design, not min(service A, generator A).

Use the exact equipment, dimensions, current ratings, operating conditions and applicable requirements described in the selected mode. Unknown values are not replaced by a generic wire, device count or capacity. Illustrative examples are arithmetic examples, not an approved installation.

Save planning case keeps an explicit local history entry. Copy MD retains current inputs, source notes and interpretation; Download CSV exports the current result breakdown. Export a separate copy before changing devices or clearing browser storage.

About Transfer Switch Path Rating Calculator

Screen actual transfer-switch candidates against independently specified normal and emergency current-path requirements. A whole-service installation can need a 200A normal path with a much smaller generator path. These requirements must come from the approved topology and protection design, not min(service A, generator A).